feat: enhance TUI with markdown, scrolling, and improved input handling

cmd/sidekick-tui/tui_test.go

@@ -23,6 +23,10 @@ func TestInitialModel(t *testing.T) {
 	if m.textarea.Value() != "" {
 		t.Errorf("expected empty textarea, got %s", m.textarea.Value())
 	}
+	
+	if len(m.history) != 1 {
+		t.Errorf("expected 1 initial message in history, got %d", len(m.history))
+	}
 }
 
 func TestModelUpdate(t *testing.T) {
@@ -52,22 +56,24 @@ func TestModelUpdate(t *testing.T) {
 	if rm.isThinking != false {
 		t.Error("expected model to stop thinking after response")
 	}
-	if len(rm.messages) < 2 {
-		t.Error("expected message list to grow after response")
+	if len(rm.history) < 2 {
+		t.Error("expected history list to grow after response")
 	}
 }
 
 func TestMessageWrapping(t *testing.T) {
 	m := initialModel()
 	m.ready = true
+	m.width = 10
+	m.height = 20
 	m.viewport = viewport.New(10, 5) // Very narrow
 	
 	longMsg := "This is a very long message that should be wrapped."
 	respModel, _ := m.Update(agentResponseMsg{response: longMsg})
 	rm := respModel.(model)
 	
-	lastMsg := rm.messages[len(rm.messages)-1]
-	if !strings.Contains(lastMsg, "\n") {
-		t.Errorf("expected long message to be wrapped, but no newline found")
+	content := rm.viewport.View()
+	if !strings.Contains(content, "\n") {
+		t.Errorf("expected long message to be wrapped, but no newline found in viewport")
 	}
 }